IT HAS BEEN SHOWN THAT LANTHANUM OXIDES CAN SUBSTANTIALLY MODIFY THE CHEMICAL BEHAVIOUR OF HIGHLY DISPERSED METAL CATALYSTS [1]. IN THIS SYSTEM, SEVERAL CHEMICAL SPECIES ARE PRESENT SUCH AS LA2O3 OR LA(OH)3, WHICH COULD BE IMPLIED IN THE ELECTRO OXIDATION OF ALCOHOLS LIKE METHANOL OR ETHANOL, FOR EXAMPLE. IN THE PAST DECADES, DIRECT ALCOHOL FUEL CELLS (DAFCS) HAVE RECEIVED MUCH ATTENTION DUE TO THEIR POSSIBLE APPLICATIONS IN TRANSPORTATION AND PORTABLE ELECTRONIC DEVICES. METHANOL OR ETHANOL CAN BE DIRECTLY USED AS FUEL IN DAFCS WITHOUT EXTERNAL REFORMER. ETHANOL HAS HIGHER ENERGY DENSITY COMPARED WITH METHANOL AND IT IS MORE ATTRACTIVE AS FUEL FOR DAFCS. IT IS ACCEPTED THAT THE COEXISTENCE OF SOME METAL OXIDES WITH NI CAN IMPROVE THE CATALYTIC ACTIVITY OF NI-BASED CATALYSTS FOR THIS REACTION. ELECTROCATALYTIC ACTIVITY TOWARD ETHANOL ELECTROOXIDATION OF NI PARTICLES IN NILA/C CATALYSTS WITH DIFFERENT NI:LA RATIOS HAS BEEN STUDIED WITH DIFFERENT ELECTROCHEMICAL AND SPECTROSCOPIC TECHNIQUES, AND THE RESULTS WERE COMPARED TO THOSE OF NI/C CATALYST. SIGNIFICANT ENHANCEMENT IN THE ELECTROCATALYTIC ACTIVITY HAS BEEN ACHIEVED BY DEPOSITING THE NI PARTICLES WITH LANTHANUM OXIDES/HYDROXIDES USING AN ALCOHOL REDUCTION METHOD. COMPARED TO NI/C CATALYST, NILA/C MATERIALS EXHIBIT A LOWER ONSET POTENTIAL AND A HIGHER ELECTRON-TRANSFER RATE CONSTANT FOR THE INVESTIGATED REACTION. THESE STUDIES ILLUSTRATE THE POSSIBILITY OF UTILIZING NI/C WITH LA OXIDES/HIDROXIDES AS ELECTROCATALYST FOR DIRECT ALCOHOL FUEL CELLS (DAFCS). THE COMBINATION OF ELECTROCHEMICAL AND SPECTROSCOPIC TECHNIQUES HAS ALLOWED A COMPARATIVE ANALYSIS OF THE BEHAVIOR OF NI/C, NILA/C (40:60) AND NILA/C (20:80) ELECTROCATALYSTS TOWARDS ETHANOL ELECTROOXIDATION. A SIGNIFICANT INCREASE OF PERFORMANCE WAS OBSERVED WITH THE INCREMENT OF LA OXIDES/HIDROXIDES CONTENT, INDICATING THAT THE ADDITION OF LA SPECIES IMPROVES THE ACTIVITY OF NI FOR THIS REACTION. ALSO THE FORMATION OF CO2 IS FAVOURED IF THE LA OXIDES/HYDROXIDES CONTENT IS RAISED TO NI:LA 20:80, AND, THUS, THE PRESENCE OF THESE COMPOUNDS AS OXYGEN SOURCE CAN FAVOR BOTH BULK ALCOHOL REACTIONS (ACETIC ACID FORMATION) AND ADSORBED SPECIES OXIDATION (CO2 PRODUCTION). THE INITIATION FOR ETHANOL OXIDATION IS OBSERVED AT 0.50 V, THAT IS, IN THE POTENTIAL RANGE USED FOR A DAFC. THE ENHANCEMENT OF ACTIVITY TOWARDS ALCOHOL ELECTROOXIDATION IN THIS POTENTIAL REGION DUE TO THE ADDITION OF LA OXIDES/HIDROXIDES TO NI OPENS A POSSIBILITY TO UTILIZE THESE MATERIALS AS ELECTROCATALYSTS FOR THESE DEVICES [1, 2]. HOWEVER, THE DETECTION OF REPRESENTATIVE AMOUNTS OF ACETIC ACID CLEARLY INDICATES THAT THE C-C BOND IS NOT COMPLETELY BROKEN AND FURTHER OPTIMIZATION OF THE CATALYSTS IS NEEDED TO IMPROVE THE ENERGY EFFICIENCY OF ETHANOL ELECTROOXIDATION.

PT-SN-SNO2 AND PT-SN CATALYSTS SUPPORTED ON CARBON WERE SYNTHESIZED BY A MODIFIED POLYOL METHOD. AN ELECTROCHEMICAL STUDY SHOWED THAT THE PT-SN-SNO2/C CATALYST HAD A BETTER PERFORMANCE COMPARED WITH THE PT-SN/C CATALYST. CHRONOAMPEROMETRY EXPERIMENTS OF THE ASPREPARED CATALYSTS SHOWS THAT THE ACTIVITY FOR ETHANOL OXIDATION OF PT-SN-SNO2/C IS HIGHER THAN THAT OF PT-SN/C.

AN INTERESTING ALTERNATIVE TO H2-FUELED PEMFC FOR PORTABLE AND MOBILE APPLICATION IS THE USE OF ETHANOL AS A FUEL (DEFC) [1]. MANY STUDIES HAVE POINTED PT-SN/C AS THE BEST ELECTROCATALYST FOR ETHANOL ELECTRO-OXIDATION (EOR) IN ACID ENVIRONMENT. HOWEVER, THESE KINDS OF ALLOYS USUALLY SHOW RELATIVELY LOW SELECTIVITY FOR CO2 FORMATION COMPARED WITH PT ALONE [2]. ZHU ET AL. [3] SYNTHESIZED PT-SNO2 AND PTSN ALLOY CATALYST. THE ANALYSIS OF THE PRODUCTS SHOWS THAT ADDITION OF SNO2 ENHANCED THE TOTAL OXIDATION TO CO2.IN THIS WORK, WE SYNTHESIZED SNO2 BY AN EX SITU METHOD AND MADE A BINARY CATALYST BY ADDING A TIN OXIDE TO PT AND ITS PERFORMANCE COMPARED WITH PT-SN. PT-SNO2 AND PT-SN CATALYSTS SUPPORTED ON CARBON WERE SYNTHESIZED BY A MODIFIED POLYOL METHOD. THE XRD ANALYSIS SHOWED THE ALLOY CATALYST WAS SYNTHESIZED. ELECTROCHEMICAL TESTS SUCH AS CV,LSV, CHORNOAMPEROMETRY AND EIS WERE PERFORMED FOR TWO CATALYSTS. THE CV RESULTS INDICATE THAT THE ONSET POTENTIAL OF TWO CATALYSTS WAS SAME BUT THE RATIO OF IF/IB (CO2 TOLERANCE) FOR PT-SNO2 WAS GREATER THAN PT-SN. THE EIS TECHNIQUE WAS USED TO INVESTIGATE THE CATALYTIC ACTIVITY FOR THE CO OXIDATION AND PT-SNO2 HAVE A BETER TOLERANCE TO CO2.

INVESTIGATION OF ELECTROOXIDATION PROCESSES OF ALCOHOLS IS CRITICAL IN ATTAINING A BETTER UNDERSTANDING OF THE DIRECT ALCOHOL FUEL CELL (DAFC). THE DIRECT METHANOL FUEL CELL (DMFC) HAS RECENTLY RECEIVED A GOOD DEAL OF ATTENTION FOR BOTH MOBILE AND STATIONARY APPLICATIONS. THE CATALYTIC OXIDATION OF METHANOL WAS INVESTIGATED BY ELECTROCHEMICAL METHODS AT A NICKLE (II) COMPLEX MODIFIED CARBON PASTE ELECTRODE (CPE) IN ALKALINE SOLUTION. THIS STUDY SHOWS THAT MODIFIED ELECTRODE HAD ELECTROCATALYTIC ACTIVITY FOR OXIDATION OF METHANOL. IT WAS FOUND THAT METHANOL WAS OXIDIZED BY NIOOH GENERATED WITH FURTHER ELECTROCHEMICAL OXIDATION OF NICKEL HYDROXIDE ON THE SURFACE OF THE MODIFIED ELECTRODE. THE RATE CONSTANT OF THE CATALYTIC PROCESS AND ELECTRON TRANSFER COEFFICIENT WERE CALCULATED TO BE 1.65 S-1 AND 0.41 RESPECTIVELY. THE PEAK POTENTIAL FOR THE OXIDATION OF METHANOL AT THIS MODIFIED ELECTRODE WAS 620 MV. THE ANODIC PEAK CURRENTS SHOW LINEAR DEPENDENCY WITH THE SQUARE ROOT OF SCAN RATE. THIS BEHAVIOR IS THE CHARACTERISTIC OF A DIFFUSION CONTROLLED PROCESS AND THE DIFFUSION COEFFICIENT OF METHANOL WAS FOUND TO BE 5.29X10-5 CM2S-1 AND THE NUMBER OF ELECTRON WAS CALCULATED TO BE 1.